Roup, Lander, Powell, and Hoffman (in press)
Purpose: This study examined the impact of traumatic brain injury (TBI) on self-perceived hearing and suprathreshold binaural processing in young and middle-aged adults.
Method: Ninety-three adults with normal hearing (thresholds ≤25 dB HL 250-4000 Hz) participated in one of four groups: 38 young adults, 23 young adults with TBI, 16 middle-aged adults, and 16 middle-aged adults with TBI participated. Self-perceived hearing difficulty was measured via questionnaires. Binaural processing was measured using dichotic word recognition, the Listening in Spatialized Noise-Sentences test, and the 500-Hz masking level difference. For each participant, a composite binaural processing (CBP) score was calculated to obtain a global metric of binaural processing performance. The CBP was composed of six measures from the three behavioral tests, including the S0N0 and SπN0 thresholds from the 500-Hz MLD, the low- and high-cue speech recognition thresholds from the LiSN-S, and the free and directed recall ear advantages from the dichotic words test.
Results: The middle-aged TBI group reported significantly greater degrees of self-perceived hearing difficulty than the other groups. On average, the middle-aged TBI group performed poorer on the individual binaural processing tests, however, the differences were significant for the S0N0 and SπN0 masking level difference thresholds only. Results for the global metric of binaural processing revealed significantly poorer CBP scores for the middle-aged TBI group compared to the other groups.
Conclusions: Results demonstrate that both age and a positive history of TBI contributed to deficits in suprathreshold binaural processing. Middle-aged adults with a history of TBI are at risk for experiencing pre-senescent deficits in suprathreshold binaural processing deficits, despite having clinically normal hearing.